GB1586932A

GB1586932A - Thread tension compensating apparatus

Info

Publication number: GB1586932A
Application number: GB7456/78A
Authority: GB
Original assignee: Maschinenfabrik Rieter AG
Current assignee: Maschinenfabrik Rieter AG
Priority date: 1977-03-01
Filing date: 1978-02-24
Publication date: 1981-03-25
Also published as: DE2803378C2; FR2382395A1; IT7819083A0; CH615647A5; DE2803378A1; IT1091866B; FR2382395B1

Abstract

One arm of the thread-tension compensator (5) for a winding device has a leaf spring (13) embedded in the middle part in two elastomeric elements (15). One end of the spring is clamped to a roller carrier (12) and the other end of the spring is clamped in a mounting (14) fastened to the machine stand (17). By means of the thread-tension compensator (5), the change in tension of the thread (1) caused by a traversing device (11) is compensated. <IMAGE>

Description

(54) THREAD TENSION COMPENSATING APPARATUS (71) We, MASCHINENFABRIK RIE TER A.G. a body corporate organised under the laws of Switzerland, of Winterthur, Switzerland, do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a support arm for a thread tension compensating apparatus of a winding machine, having a take-off roller a take-up bobbin and a yarn traversing device for traversing thread longitudinally of the bobbin. The term 'thread" as used herein includes "yarn".

On winding machines, the yarn is traversed to and fro during the winding process. In a traversing process of such nature, a periodic variation in the length of the path, along which the yarn moves inevitably occurs as the distance between the take-off roller, or the last guide roller respectively, and the lateral end of the bobbin package exceeds the corresponding distance to the centre of the bobbin package. This length variation and the yarn tension variation generated thereby are normally compensated for by guiding the yarn over a yarn tension compensating device between the take-off roller and the bobbin package. Known yarn tension compensating devices comprise a deflecting roller connected to a pivotable arm. This deflecting roller can be moved freely along the pivoting path. Depending on the instantaneous yarn tension. i.e. depending on the position of the traversing device at any distance, the deflecting roller is pivoted to a greater or less extent away from a rest position towards which it tends to move under the influence of a re-setting force exerted for example. by. a counterweight or by a spring. Such known yarn tension compensating devices have the disadvantage that at high winding speeds, and thus at necessarily high traversing frequency of the yarn traversing guide, the deflecting roller tends to vibrate in uncontrolled manner under the influence of inertia forces.

In one known yarn tension compensating device this disadvantage is avoided by using a pivotable double arm which is pivotable about a fixed pivoting centre, one arm supporting the deflecting roller and the other arm supporting a counterweight. The side of the arm supporting the counterweight is connected to two opposed springs each having one end fixed to the arm and the other end fixed to the machine frame. In this manner, each deviation of the deflecting roller is dampened by the correspondingly counteracting spring. However, uncontrolled vibrations of the deflecting roll still occur at high winding speeds.

It is an object of the present invention, to provide means by which the deflecting roller reliably compensates for the periodic length variations in yarn path length or in yarn tension respectively.

According to this invention, there is provided a support arm for a tension compensating apparatus of a thread winding machine of the kind having a take-off roller, a take-up bobbin and a thread traversing device for traversing thread longitudinally of the bobbin, the said arm comprising a leaf spring having a first portion adapted to be fixed to a support in the machine, a second portion fixed to a roller support and an intermediate portion between said first and second portions, the said intermediate portion being embedded in a rubber-elastic element whereby, when in use, the arm can, via said second portion, support a roller to contact the thread between the take-off roller and the take-up bobbin to compensate thread tension variations generated by the thread traversing movement.

The rubber-elastic element is preferably adhered to the leaf spring. It may also be advantageous if the leaf spring is of spring steel and if the rubber-elastic element are of polymerised chloroprenes. A further advantage can be obtained, if the leaf spring is fixed in such a manner that the rubberelastic element is, even in the rest position of the yarn tension compensating apparatus, compressed in the longitudinal direction of the arm.

The present invention will now be described with reference to the single figure of the accompanying drawing which schematically illustrates a winding device of a drawwinding machine with a yarn tension compensating apparatus.

In the arrangement illustrated, a yarn or thread 1 is guided by a draw-roller 2 with a separator roller 3 (which rollers also act as take-off rollers) of a drawing device not shown in detail. The yarn or thread passes over a deflecting roller 4 of a lever-shaped yarn tension compensating apparatus 5, before it is wound on a bobbin package 6.

The bobbin package 6 is built up on a bobbin tube 7, which is supported on a rotatable shaft 8. The bobbin package 6 is driven by a friction drive drum not shown in the drawing. Before the yarn 1 is wound on .the package 6, it is traversed to and fro in known manner by a traversing yarn guide 9 movable in a slot 10 of a traversing device 11.

The yarn tension compensating apparatus 5 comprises a roller support 12 rotatably supporting the deflection roller 4. An end of a leaf spring 13 made of spring steel extends into a slot 20, is screwed on the roller support 12 by means of a screw 18 and is fixed in the roller support 12. The other end of the leaf spring 13 is screwed by means of a screw 16 into a support member 14 consisting of two steel blocks and is clamped between the two steel blocks. The screw 16 is also used for mounting the lever-shaped yarn tension compensating apparatus 5 on a plate 17 of a machine frame which is not shown in greater detail. Two halfs of a rubber-elastic element 15 are adhesively bonded to the flat spring 13 between the support member 14 and the roller support 12.

During the winding process. the length of the yarn path between the deflection roller 4 and the winding point on the bobbin package changes periodically as indicated schematically in the drawing by the yarn paths 1, 1', 1" These variations in length and the yarn tension variations generated by them, are compensated by the yarn tension compensating apparatus 5, as its deflecting roller 4 is periodically moved up and down about the axis of rotation A. as indicated by the double arrow 19. During movement of the yarn from the position l' to the position 1", the deflecting roller 4, with the roller support 12, rises and falls once between a position more deflected down from the horizontal position of the arm and a position less deflected down. In this operation, the rubber-elastic element 15 effects a dampening influence opposed to the movement of the deflecting roller 4.

It has been found, that the yarn tension compensating apparatus hereinbefore described functions extremely reliably and periodically compensates the yarn tension variations, without uncontrolled vibrations of the deflecting roller 4 occurring. If the leaf spring 13 is fixed in such a manner that the rubber-elastic element 15 is, even in the state of rest of the yarn tension compensating apparatus, compressed to a determined degree between the support member 14 and the roller support 12, a particularly good dampening action of the rubber-elastic element can be achieved. The rubber-elastic element 15, which counteracts the movement of the deflecting roller 4, is preferably made of polymerised chloroprenes. However, an element made of any other rubberelastic material may also be used. In the illustrated embodiment, the leaf spring 13, the support 14, the rubber-elastic element 15 and the pivoting arm 5 are of the same width, and, all except the spring 13, are also of approximately the same height. Instead of adhesively bonding the two parts of the rubber-elastic element 15 to the spring 13, the two parts may also be vulcanized to the spring.

The support arm of the invention may be used not only on a draw-winding machine, but also on the winding or spooling unit of any desired winding machine.

A further advantage is that the simple clamping of the flat spring with the connected rubber-elastic element in the support member and in the roller support permit easy exchange of this element in such manner that according to the fineness of the yarn to be wound, parts with various thickness of the leaf spring can be kept in storage.

WHAT WE CLAIM IS: 1. A support arm for a tension compensating apparatus of a thread winding machine of the kind having a take-off roller, a take-up bobbin and a thread traversing device for traversing thread longitudinally of the bobbin, the said arm comprising a leaf spring having a first portion adapted to be fixed to a support in the machine, a second portion fixed to a roller support and an intermediate portion between said first and second portions, the said intermediate portion being embedded in a rubber-elastic element whereby, when in use, the arm can, via said second portion, support a roller to contact the thread between the take-off

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. adhered to the leaf spring. It may also be advantageous if the leaf spring is of spring steel and if the rubber-elastic element are of polymerised chloroprenes. A further advantage can be obtained, if the leaf spring is fixed in such a manner that the rubberelastic element is, even in the rest position of the yarn tension compensating apparatus, compressed in the longitudinal direction of the arm. The present invention will now be described with reference to the single figure of the accompanying drawing which schematically illustrates a winding device of a drawwinding machine with a yarn tension compensating apparatus. In the arrangement illustrated, a yarn or thread 1 is guided by a draw-roller 2 with a separator roller 3 (which rollers also act as take-off rollers) of a drawing device not shown in detail. The yarn or thread passes over a deflecting roller 4 of a lever-shaped yarn tension compensating apparatus 5, before it is wound on a bobbin package 6. The bobbin package 6 is built up on a bobbin tube 7, which is supported on a rotatable shaft 8. The bobbin package 6 is driven by a friction drive drum not shown in the drawing. Before the yarn 1 is wound on .the package 6, it is traversed to and fro in known manner by a traversing yarn guide 9 movable in a slot 10 of a traversing device 11. The yarn tension compensating apparatus 5 comprises a roller support 12 rotatably supporting the deflection roller 4. An end of a leaf spring 13 made of spring steel extends into a slot 20, is screwed on the roller support 12 by means of a screw 18 and is fixed in the roller support 12. The other end of the leaf spring 13 is screwed by means of a screw 16 into a support member 14 consisting of two steel blocks and is clamped between the two steel blocks. The screw 16 is also used for mounting the lever-shaped yarn tension compensating apparatus 5 on a plate 17 of a machine frame which is not shown in greater detail. Two halfs of a rubber-elastic element 15 are adhesively bonded to the flat spring 13 between the support member 14 and the roller support 12. During the winding process. the length of the yarn path between the deflection roller 4 and the winding point on the bobbin package changes periodically as indicated schematically in the drawing by the yarn paths 1, 1', 1" These variations in length and the yarn tension variations generated by them, are compensated by the yarn tension compensating apparatus 5, as its deflecting roller 4 is periodically moved up and down about the axis of rotation A. as indicated by the double arrow 19. During movement of the yarn from the position l' to the position 1", the deflecting roller 4, with the roller support 12, rises and falls once between a position more deflected down from the horizontal position of the arm and a position less deflected down. In this operation, the rubber-elastic element 15 effects a dampening influence opposed to the movement of the deflecting roller 4. It has been found, that the yarn tension compensating apparatus hereinbefore described functions extremely reliably and periodically compensates the yarn tension variations, without uncontrolled vibrations of the deflecting roller 4 occurring. If the leaf spring 13 is fixed in such a manner that the rubber-elastic element 15 is, even in the state of rest of the yarn tension compensating apparatus, compressed to a determined degree between the support member 14 and the roller support 12, a particularly good dampening action of the rubber-elastic element can be achieved. The rubber-elastic element 15, which counteracts the movement of the deflecting roller 4, is preferably made of polymerised chloroprenes. However, an element made of any other rubberelastic material may also be used. In the illustrated embodiment, the leaf spring 13, the support 14, the rubber-elastic element 15 and the pivoting arm 5 are of the same width, and, all except the spring 13, are also of approximately the same height. Instead of adhesively bonding the two parts of the rubber-elastic element 15 to the spring 13, the two parts may also be vulcanized to the spring. The support arm of the invention may be used not only on a draw-winding machine, but also on the winding or spooling unit of any desired winding machine. A further advantage is that the simple clamping of the flat spring with the connected rubber-elastic element in the support member and in the roller support permit easy exchange of this element in such manner that according to the fineness of the yarn to be wound, parts with various thickness of the leaf spring can be kept in storage. WHAT WE CLAIM IS:

1. A support arm for a tension compensating apparatus of a thread winding machine of the kind having a take-off roller, a take-up bobbin and a thread traversing device for traversing thread longitudinally of the bobbin, the said arm comprising a leaf spring having a first portion adapted to be fixed to a support in the machine, a second portion fixed to a roller support and an intermediate portion between said first and second portions, the said intermediate portion being embedded in a rubber-elastic element whereby, when in use, the arm can, via said second portion, support a roller to contact the thread between the take-off

roller and the take-up bobbin to compensate thread tension variations generated by the thread traversing movement.

2. An arm according to Claim 1, wherein the rubber-elastic element is composed of two parts which are adhered to oppositely facing surfaces of the leaf spring.

3. An arm according to Claim 2 wherein the two parts of the element are adhesively bonded to the spring.

4. An arm according to claim 2, wherein the two parts of the element are vulcanised on the spring.

5. An arm according to any preceding claim wherein the leaf spring is of spring steel.

6. An arm according to any preceding claim, wherein the rubber-elastic element is of polymerised chloroprenes.

7. An arm according to any preceding claim wherein the first portion of the spring is adapted to be fixed to said support by being clamped between portions of a mounting member for mounting the arm on the support.

8. An arm according to Claim 7 wherein the leaf spring is clamped in the mounting member and is fixed to the roller support in such a manner that the element is compressed in the longitudinal direction of the arm even when the tension compensating apparatus is in a rest position in use.

9. A tension compensating apparatus comprising an arm as claimed in any preceding claim and a roller mounted in said roller support.

10. A yarn tensioning compensating apparatus substantially as described with reference to the accompanying drawing.

11. A winding machine comprising a tension compensating apparatus as claimed in claim 9 or claim 10.